Debt - Convertible Senior Notes - Liability and Equity Components (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Liability component
Principal	$ 433,484	$ 433,484
Debt discount and issuance costs, net	(52,254)	(56,364)
Convertible senior notes | 2025 Notes
Liability component
Principal	192,500	192,500
Debt discount and issuance costs, net	(50,768)	(54,597)
Net carrying amount	141,732	137,903
Equity component, net	$ 65,361	$ 65,361